Department of Biology and Marine Program, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
Department of Biology and Marine Program, Boston University, 5 Cummington Mall, Boston, MA 02215, USA.
Proc Biol Sci. 2018 Nov 21;285(1891):20181295. doi: 10.1098/rspb.2018.1295.
In social groups, high reproductive skew is predicted to arise when the reproductive output of a group is limited, and dominant individuals can suppress subordinate reproductive efforts. Reproductive suppression is often assumed to occur via overt aggression or the threat of eviction. It is unclear, however, whether the threat of eviction alone is sufficient to induce reproductive restraint by subordinates. Here, we test two assumptions of the restraint model of reproductive skew by investigating whether resource limitation generates reproductive competition and whether the threat of eviction leads to reproductive restraint in the clown anemonefish First, we use a feeding experiment to test whether reproduction is resource limited, which would create an incentive for the dominant pair to suppress subordinate reproduction. We show that the number of eggs laid increased in the population over the study period, but the per cent increase in fed groups was more than twice that in unfed groups (205% and 78%, respectively). Second, we use an eviction experiment to test whether the dominant pair evicts mature subordinates, which would create an incentive for the subordinates to forgo reproduction. We show that mature subordinates are seven times more likely to be evicted than immature subordinates of the same size. In summary, we provide experimental support for the assumptions of the restraint model by showing that resource limitation creates reproductive competition and a credible threat of eviction helps explain why subordinates forego reproduction. Transactional models of reproductive skew may apply well to this and other simple systems.
在社会群体中，如果群体的繁殖输出受到限制，并且占优势的个体可以抑制从属个体的繁殖努力，那么高繁殖偏度预计会出现。繁殖抑制通常被认为是通过明显的侵略或驱逐的威胁来发生的。然而，仅仅是驱逐的威胁是否足以诱导从属个体的生殖抑制还不清楚。在这里，我们通过调查资源限制是否会产生繁殖竞争，以及驱逐的威胁是否会导致小丑鱼的生殖抑制，来检验生殖偏度的抑制模型的两个假设。首先，我们使用喂食实验来测试繁殖是否受到资源限制，这将为优势对抑制从属繁殖创造动力。我们发现，在研究期间，种群中产卵的数量增加了，但在喂食组中的增加百分比是未喂食组的两倍多（分别为 205%和 78%）。其次，我们使用驱逐实验来测试成熟的从属个体是否会被优势对驱逐，这将为从属个体放弃繁殖创造动力。我们发现，成熟的从属个体被驱逐的可能性是同体型的未成熟从属个体的七倍。总之，我们通过展示资源限制产生繁殖竞争和驱逐的可信威胁，为抑制模型的假设提供了实验支持。生殖偏度的交易模型可能适用于这种和其他简单系统。
